by Eric Prisbell, USA TODAY Sports

by Eric Prisbell, USA TODAY Sports

OKLAHOMA CITY - James Harden said he experienced some awkward moments before his postseason return to Chesapeake Energy Arena, where much of the fan base that he had grown accustomed to in three years serenaded him with boos.

Once Game 1 of the NBA playoff series began, it only grew more uncomfortable for Harden. In making his return to the familiar and now unfriendly confines of this arena, Harden experienced firsthand why the Oklahoma City Thunder could be every bit as formidable without him.

The Thunder, the top seed in the Western Conference, broke open a tight game in the second quarter and cruised to a 120-91 victory over the eighth-seeded Houston Rockets, who are heavy underdogs playing in their first postseason series since the 2008-09 season.

Kevin Durant scored 24 points, Russell Westbrook added 19 and Serge Ibaka had 17. The one name missing from that touted Oklahoma City group is Harden's.

"It felt a little awkward looking across there during the national anthem and seeing him with another team," Durant said. "But we have to get past that. He wants to win so bad. ... It's fun to play against him, but it was a little different."

Harden was a key cog in the Thunder franchise before they traded him in October after failing to agree on a contract extension with the reigning NBA sixth man of the year. And now Harden, who became an All-Star and the league's fifth-leading scorer, is attempting to steward a team laden with several players making their first career playoff appearance.

And it showed. Harden used the word "shell-shocked" to describe his team, which missed its first nine field goals attempts in the game. He said a resounding defeat like this one "was definitely good for us. Now we know how to play. We'll watch film and get better at it."

Harden had 20 points on 6-of-19 shooting, but no other Rockets starter finished in double figures. And a team that averaged 106 points during the regular season finished 15 points below that average, shooting 36.3% from the floor and 22% from three-point range.

Rockets coach Kevin McHale said players bobbled balls around the paint, missed point-blank shots and exhibited nerves during the early stages of the game.

As for the Thunder, who have taken incremental steps forward in the playoffs the past three seasons, they avoided any dose of adversity other than squandering a 13-point first-quarter advantage. But with the game tied at 40 in the second quarter, Thunder coach Scott Brooks said, he told his team that every minute counted.

The Thunder finished the half on a 20-7 run in a little more than five minutes, seizing control of the game.

"We knew that this team could make runs," Brooks said. "We missed some shots during their run, then we caught fire. We wanted to focus on those last five minutes. You can really impact a game in the end there. The guys did a good job, if not a great job, closing out that second quarter."

Before the game, Harden said it would be "interesting" to see how fans greeted him upon his return to Oklahoma City in the playoffs. He signed about a dozen autographs and hugged a security guard before entering the locker room after warming up. But during player introductions, he was serenaded with a chorus of boos, which he heard again when he went to the free throw line early in the game.

With 8:32 left in the first quarter, Harden found himself covering Durant. The Thunder star cut to the basket, and Ibaka found him with a bounce pass for a layup that gave the home team an eight-point advantage.

And Harden said he was also surprised when Durant jumped in front of him during the game, drawing a charge.

Playing against Harden "was fun," said Westbrook, who also had 10 assists and eight rebounds in just more than 30 minutes of action. "James is competitive and has his own team now. But me and Kevin are here and will compete for our team as well."

The Rockets will have two days to prepare before Wednesday's Game 2, and they will need it after they were schooled in playoff basketball by a team that expects to be playing long into June.